The present invention relates to an automatic blood pressure monitoring apparatus, more particularly, to ambulatory blood pressure monitoring.
A number of portable monitoring devices are used in medical monitoring. One well known device is the so-called Holter monitor which is an EKG monitor which typically uses a magnetic tape recording to record EKG signals from a patient over extended periods of time. Another is a portable monitor for obtaining blood pressure readings over extended periods of time. An example of such a monitor is the Model 5200 ambulatory blood pressure monitor sold by SpaceLabs, Inc. of Redmond, WA.
The Model 5200 comprises a blood pressure cuff, an air pump for activating the blood pressure cuff, a pressure transducer for generating electrical signals representative of the pressure in said cuff, circuitry and means for processing the electrical signals and a removable RAM package for storing the blood pressure data resulting from processing the electrical signals.
In the prior art, one air hose is provided from the air pump to the cuff bladder to pump up the cuff and to bleed the cuff while a second air hose is provided between the bladder and the pressure transducer for sensing the cuff pressure by the pressure transducer.
Unwanted surges of pressure as the bladder is pumped up or as stepped bleeding occurs are coupled into the pressure transducer which causes unwanted noise or spurious electrical signals to be generated by the transducer. Also, in the particular case of an ambulatory monitor which is often worn by the patient all day and night, the smaller and lighter the monitor, the better. In particular it is desirable to reduce the number of air hoses which must be coupled to the cuff from the usual two hoses to one hose.